Piston for hypodermic syringes, &amp;c.



P. J. MUELROY.

PISTON FOR HYPODERMIG SYRINGBS, &c.

APPLICATION FILED APR. 16. 1912.

1,036,679, v Patented Aug. 2?,"1912.

diiesse: Inventar WM I WM'IMZQMM COLUMBIA PLANDORAPH cu.,wAsHiNu'roN. D. c.

PATRICK J. MCELROY, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TO THE RANDALL-FAICHNEY COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORA- TION OF MASSACHUSETTS.

.PISTON FOR HYPODERMIC SYRINGES, &G.

Application filed April 16, 1912. Serial No. 691,129.

To all whom it may concern:

Be it known that I, PATRICK J. MoELnoY, a citizen of the United States, and a resident of Cambridge, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Pistons for Hypodermic Syringes, Sac., of which the following is a specification.

This invention relates to a hypodermic syringe piston of asept-ic character and composed of a rod of glass or other vitreo-us material, and a compressible packing of refrac tory material such as asbestos, adapted to be sterilized by contact with a flame.

A piston of this character is shown by Letters Patent of t-he United States No. 788,059, dated April 25, 1905, said piston comprising a rod or stem provided with confining abutments and a compressible refractory packing filling the space between the` abutments. Asbest-os buffer threads are secured to the outer abutment and extend across the outer side of the same, said threads being intended to prevent injurious impact of the rod with the outlet'end of the glass barrel of the syringe. They have not, however, been heretofore arranged to form a continuous buffer adapted to protect all the vitreous surfaces at the outer end of the rod from contact with a sterilizing fiame, the buffer being of skeleton form having nu! merous openings which expose portions of the vitreous surfaces, these being liable to be fused or broken by the insertion of the piston in a flame. Moreover, said openings form pockets which retain portions of the liquid with which the barrel is charged, s0 that the entire charge of liquid cannot be ejected, and entire accuracy in the administration of toxins and serums, which is very desirable, and in many cases highly important, cannot be obtained, a few minims of the liquid, the exact quantity of which is uncertain, remaining in the barrel after the piston has ejected all that is possible.

The present invention has for its object to provide a piston of the character stated having a buffer which is not only adapted to prevent injury to the vitreous rod by a sterilizing flame, but -also to insure the ejection of all the liquid from the syringe barrel.

To these ends the invention consists in the closely spaced transverse notches 15.

improvements which I will now proceed to describe and claim. i

Of the accompanying drawings Figure 1 represents a side elevation of a syringe piston embodying my invention. Fig. 2 represents an end view of the saine. Fig. 3

represents a side view of the outer end portion of the piston rod, the packing and buffer being removed. Fig. l represents an end view of the rod as shown by Fig. 3.

Specification of Letters Patent.A lan'td` Aug. 27, 1912. i

Fig. 5 represents a view similar to Fig. 4 v

showing the commencement of the operation of forming t-he buffer.` Fig. 6 represents a section on line G46 of F 5. Fig. 7 represents a view similar to Fig. 5 showing the operation of forming4 the buffer further advanced. Fig. 8 represents a section on line 8-8 of Fig. 2.

The same reference characters indicate the same parts in all the figures.

In the drawings: 12 represents a piston rod of glass having a reduced end portion 13, and a flange 14 forming a packing abutment at the outer end of the reduced portion 13.`

4The flange 111, which` is integral with the rod 12, is provided with a plurality of The flange 14 constitutes an abutment for the compressible packing and a seat or support for the compressible refractory buffer neXt described.

The buffer is preferably composed of asbestos threads 16 applied in the manner indicated. by Figs. 5 and 6, each thread being placed against the outer side of the abutment 14 and bent over the periphery thereof. In forming a continuous buffer free from pockets or openings, I apply the threads 16 so that portions cross each other fined thereon by a helically wound asbestos Vthread or threads forming the packing 18.

Said packing secures the buffer to the rod and is confined against endwise movement by the abutment 14, the portion of the periphery of the rod between the body portion `152 and the reduced portion 13, and by spurs 19 formed on the reduced portion 13. Said spurs also prevent the packing from turning on the rod.

The packing and buffer are adapted to be quickly sterilized by holding them briefly in the flame of a gasburner. The continuous buifer protects the outer sider and periphery of the abutment 14 from injury by the i flame, and the packing and t-he longitudinallyexteuding end port-ions of the threads 16 similarly protect the reduced portion of the rod and the inner side of the abutment. The intersecting, or crossing portions of the buffer threads impart acrownlng form to the louter surface of the buffer, which has a central protuberance'and is suiiciently yielding to conform closely tothe inner surface` of,

the outlet end of the usual glass barrel 21, so that the bujfer, when pressed against said outlet end, expelsall the liquid from the barrel and projects into the outlet 22, as indicated by Fig. l. The operator is therefore enabled to administer the exact .quantity of liquid desired.y

Y It" is obvious that my invention may be embodied in a syringe piston rod which is made of other than vitreous material.

A syringe piston comprising a rod having a reduced portion and a circular packing abutment at the outer end of the rod, the periphery of said abut-ment being provided with closely spaced transverse notches, a refractory buffer sterilizable by flame, and composed of intersecting asbestos threads extending radially across the outer side of the abutment and across the notched periphery thereof,v some of said threads being engaged with the said notches while others are interposed between the engaged threads, so that the buffer covers the entire .outer side surface and the periphery of the abutment and is adapted to protect said surfaces from a sterilizing flame, portions of the bufferA threads being laid longitudinally on the reduced portion of the rod, and a vrefractory compressible packing surrounding said longitudinal thread portions and securing the buer to the rod, the buffer formed by the intersecting radial threads being'c'ompressible and adapted to conform to the interior of the outlet end of a syringe barrel, and eject all the liquid therefrom,

and having a central protuberance adapted to project into the barrel outlet. v In testimony whereof l have `aflixed my signature, in presence of two witnesses'.

j Witnesses:

C. F. BROWN, n, P. PEZZETTI.

Copies of this patent may be obtained for cents. each, by Vadlressin-g' the i Commissioner of Iatents, Washington, D. (2.l

PATRICK J, MCELROY.v 

